1. Field of the Invention
This invention relates to methods for transforming solid graphical image files into data that represents merely the surface of the solid image.
2. Background Art
In conventional x-ray systems, a two dimensional shadow image is created based upon the different x-ray absorption characteristics of bone and soft tissues. A great improvement on the conventional x-ray system as a diagnostic tool was provided by the development of computed tomography (CT) or computerized axial tomography (CAT) systems. These CT or CAT systems are x-ray based and initially were used to produce single two dimensional views depicting transverse slices of a body, object, or patient being investigated. Three-dimensional information was thereafter assembled from CT scan data by generating data for a number of contiguous slices and using the inferential abilities of the radiologist to suggest a three dimensional representation for the various internal organs. Shaded and contoured three dimensional images can be generated by interpolation between slices from the three dimensional array of data generated by a sequence of such contiguous CT scans. In the same way, the newer magnetic resonance imaging (MRI) technology is also capable of generating three-dimensional arrays of data representing physical properties of interior bodily organs. MRI systems offer an advantage over CT systems by providing the capability to better discriminate between various tissue types, not just bone and soft tissue. MRI imaging systems are also capable of generating physiological data rather than just image data. Again, as in CT systems, MRI data is available only as a sequence of slices and interpolation between the slices is necessary to render a three dimensional image.
In recent years CT and MRI images of a patient's heart have been used to aid cardiologists and other clinicians in performing electrophysiology studies or cardiac ablation treatments to diagnose and treat arrhythmias. The three-dimensional images of the heart help the clinician visualize the location of a catheter electrode within the heart to map and treat a patient's condition. Generally, however, only a rendering of the surface of cavities within the heart is necessary or desirable. Therefore, methodologies have been developed to transform the solid, three-dimensional information from MRI or CT image data into surface data only. By manipulating only surface data, much less processing power is required and greater rendering speeds are achieved.
Several options for transforming solid, three-dimensional image data into mere surface data have previously been developed, each with benefits and drawbacks. Such positive and negative aspects generally manifest themselves in relative processing speeds, accuracy of the surface rendering, and ability to identify and discard extraneous information.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the invention is to be bound.